Metering apparatus

Abstract

Apparatus is disclosed which is adapted to repeatedly and accurately dispense predetermined amounts of fluid, especially biological fluids, onto generally planar test elements. The apparatus comprises a movable carriage for supporting and locating a dispensing device at a plurality of metering stations in an analyzer. A pair of locating means are operable in sequence to precisely locate the dispensing device relative to a test element in each of the stations.

What is claimed is: 
     
       1. In an analyzer for the chemical analysis of a sample fluid wherein metering apparatus is moved through a plurality of stations, said metering apparatus comprising dispensing means for delivering a predetermined amount of fluid to a substrate in each of said stations, the combination comprising: a carriage for receiving said dispensing means;   means for supporting said carriage for movement along a path which passes through each of said stations; and   means for positioning said carriage at each of said stations, said positioning means comprising first and second locating means at each station operable in sequence on said carriage to precisely locate said dispensing means relative to said substrate, said first locating means being operable on said carriage to locate the carriage along said path between predetermined limits and said second locating means being operable on said carriage after said first locating means to precisely locate said carriage along said path within said limits.   
     
     
       2. The combination, as recited in claim 1, wherein said carriage is pivotal between a transport position and a dispense position, said carriage is movable from station to station in said transport position and is adapted to deliver fluid to said substrate in the dispense position, said first locating means is operable on the carriage in said transport position and said second locating means is operable on the carriage in said dispense position. 
     
     
       3. The combination, as recited in claim 1, wherein said first locating means is operable in a horizontal plane, and said second locating means is operable in a horizontal plane and is adapted to define the spacing in a vertical direction between said dispensing means and said substrate. 
     
     
       4. The combination, as recited in claim 1, wherein said carriage comprises a first arm for supporting said dispensing means and a second arm at an angle to said first arm, said second arm having roller means thereon which cooperates with said positioning means. 
     
     
       5. The combination, as recited in claim 4, wherein said first locating means comprises track means for receiving said roller means. 
     
     
       6. The combination, as recited in claim 5, wherein said carriage comprises a counterbalance arm journalled on said shaft, said counterbalance arm comprising a second roller means received in said track means, and spring means connecting said second arm and said counterbalance arm. 
     
     
       7. The combination, as recited in claim 1, wherein said supporting means comprises a shaft extending through each of said stations, and said carriage is journalled on said shaft for both longitudinal and pivotal movement. 
     
     
       8. The combination, as recited in claim 1, wherein said positioning means includes means for preventing pivotal movement of said carriage except when the carriage is located at one of said stations. 
     
     
       9. In a multichannel analyzer for measuring the ionic activity of sample biological liquids deposited on a test element containing a pair of ion-selective electrodes, the combination comprising: a metering station in each of the analyzer channels, each of said stations being constructed to receive a test element for performing an analysis;   metering apparatus movable to each of said stations, said apparatus including dispensing means for depositing a predetermined amount of fluid on a test element in each of said stations and a carriage for supporting said dispensing means;   support means for said carriage, said support means including a shaft which extends along said stations, said carriage being movable along said shaft and pivotal thereabout between a transport position and a dispense position; and   means for positioning said carriage at each of said metering stations, said positioning means comprising detent means at each station for locating said carriage in said transport position between predetermined limits and second locating means at each station for locating said carriage in the dispense position within said limits and relative to a test element in a metering station.   
     
     
       10. The combination, as recited in claim 9, wherein said carriage comprises a pair of arms disposed generally perpendicular to each other, one of said arms supporting said dispensing means and the other arm being journalled on said support means. 
     
     
       11. The combination, as recited in claim 10, wherein said positioning means comprises track means having slots at each of said stations, and said other arm comprises first roller means operable in said track means and receivable in said slots. 
     
     
       12. The combination, as recited in claim 11, wherein said carriage comprises a counterbalance arm, and said counterbalance arm having roller means adapated to operate in said track means. 
     
     
       13. The combination, as recited in claim 12, wherein said other arm and said counterbalance arm are biased toward each other, and said carriage is pivotal from said transport position to said dispense position against said bias when said first roller means is received in said slots. 
     
     
       14. The combination, as recited in claim 13, wherein damper means connects said one arm and said counterbalance arm to regulate the speed at which said carriage can be pivoted. 
     
     
       15. Apparatus for depositing a predetermined amount of fluid on a test element at a plurality of stations in a chemical analyzer, said apparatus comprising: means for dispensing fluid in precise amounts and for aspirating a supply of fluid from a sample cup;   carriage means for supporting said dispensing and aspirating means for movement to each of said stations;   support means for said carriage means, said support means comprising a shaft extending adjacent each of said stations, and said carriage means being pivotal about said shaft at each of said stations between a transport position and a dispense position, said carriage means having locking means for releasably holding the carriage in the dispense position and movable therealong; and   means for positioning said carriage means at each of said stations, said positioning means comprising first locating means which is operable on said carriage means to locate said dispensing means between predetermined limits and second locating means which is operable on said carriage means for locating said dispensing means within said limits relative to a test element in a metering station.